Wavelet analysis of the Baltic region river runoff longh-term trends and fluctuations

The study of changes in river discharge and flood regime can provide important information on climate change and its impacts. Wavelet analysis offers new possibilities to study changes of river discharge patterns in regard to periodical processes on a background of climate change. In this study wavelet analysis was used to study long-term changes of river discharge in the Baltic region. Periodic oscillations of discharge intensity, and low- and high-water flow years are common for the major rivers in the Eastern Baltic region. Main frequencies of river discharge were estimated to be 14, 28, 37 years for the studied rivers. Wavelet analysis allowed to identify similarities between the river discharge regime, and thus, the factors influencing it. Years of maximal and minimal discharges for major rivers were identified and the impact of large-scale atmospheric circulation processes on the river discharge was studied.